1. Field of the Invention
The present invention relates to apparatus for cleaning substrates in the manufacturing of semiconductor devices, liquid crystal displays and the like. More particularly, the present invention relates to a spin scrubber of the type that cleans substrates one at a time to remove all sorts of foreign substances, such as particles, from a surface of the substrate.
2. Description of the Related Art
Semiconductor devices and liquid crystal displays are generally manufactured by performing various processes on substrates. A number of different contaminants adhere to the substrates as a result of these processes. Therefore, the substrates are cleaned several times throughout the course of the overall manufacturing process. Also, there is an ongoing demand for semiconductor devices having higher degrees of integration and greater reliability. Even minute contaminants affect the yield of products manufactured according to fine design rules to meet such demand. Therefore, the cleaning process is critical to the success of the manufacturing of high-end semiconductor devices and the like.
The apparatus for cleaning the substrates is typically a wet-type of apparatus that physically removes particles or impurities from a surface of a substrate. The wet-type of cleaning apparatus may be classified as batch type in which a plurality of substrates are cleaned at once in a cleaning solution, and a single wafer type in which substrates are cleaned one at a time.
A spin scrubber is a known single wafer type of cleaning apparatus in which a substrate is rotated as it is cleaned. FIG. 1 is a perspective view of a conventional spin scrubber apparatus. The spin scrubber apparatus includes an index unit 100, a first substrate-transferring portion 200, a second substrate-transferring portion 300, and a processing unit 400. The processing unit 400 includes a plurality of spin scrubbers which clean a substrate by rotating the substrate, and dispensing ultra pure water onto the rotating substrate to thereby physically remove contaminants from the surface of the substrate. The processing unit 400 may also employ a brush to assist in the scrubbing of the substrate.
A cassette 110 in which a number of substrates are stacked is mounted on the index unit 100. The first substrate-transferring portion 200 is capable of loading/unloading substrates into/from the cassette 110, and the second substrate-transferring portion 300 is capable of loading/unloading substrates into/from the spin scrubbers of the processing unit 400. The first substrate-transferring portion 200 includes an index arm 210 and the second substrate-transferring portion 300 includes a transfer arm unit 310. The index arm 210 and the transfer arm unit 310 transfer the substrates one-by-one from the index unit 100 to the processing unit 400 and vice versa until all of the substrates are cleaned.
To this end, the index arm 210 of the first substrate-transferring portion 200 of the spin scrubber apparatus and the transfer arm unit 310 of the second substrate-transferring portion 300 of the spin scrubber apparatus have working envelopes in which the index arm 210 and the transfer arm unit 310 move, respectively. These working envelopes are essentially discrete from one another; that is, the index arm 210 and the transfer arm unit 310 move along paths that extend in different directions.
In addition, the transfer arm unit 310 includes an upper arm and a lower arm. When the index arm 210 withdraws a substrate from the cassette 110, the lower arm of the transfer arm unit 310 receives the substrate from the index arm 210 and moves it to the processing unit 400. On the other hand, the upper arm of the transfer arm unit 310 withdraws substrates from the processing unit 400. Thus, a clean substrate withdrawn from the processing unit 400 by the upper arm of the transfer arm unit 310 is transferred to the index arm 210 and re-loaded into the cassette 110 by the index arm 210. These operations are carried out until the substrates in the cassette 110 are transferred from the cassette 110, cleaned and returned to the cassette 110 one-by-one.
However, the spin scrubber apparatus as described above is cumbersome because the working envelopes of the index arm 210 and the transfer arm unit 310 are basically discrete from one another. That is, the spin scrubber apparatus has a relatively large footprint. In addition, the path along which substrates are transferred between the cassette 110 and the processing unit 400 is long. Accordingly, it takes along time to clean all of the substrates in the cassette and return the cleaned substrates to the cassette. These drawbacks, namely the long processing time and large space requirements for the conventional spinner scrubber apparatus, increase the cost of manufacturing the semiconductor devices, liquid crystal displays and the like.